Releasable clamps

ABSTRACT

RELEASABLE CLAMPS ARE DESCRIBED FOR USE IN CONNECTING GUYS OR STAYS TO SCAFFOLD CONSTRUCTIONS. THE CLAMPS INCLUDE PAIRS OF PLATES IN PIVOTAL RELATIONSHIP AT LEAST ONE OF THE PLATES HAVING A HOOK IN WHICH THE SCAFFOLD TUBE CAN BE INSERTED AND THEREAFTER SECURED BY RELATIVE PIVOTAL MOVEMENT OF THE PLATES SO AS TO CAUSE THE OPEN END OF THE HOOK TO BE BRIDGED. THE PLATES ARE ARRANGED WITH THE HOOKS IN OPPOSITE HAND RELATIONSHIP TO RECEIVE A SCAFFOLD TUBE SIMULTANEOUSLY BETWEEN THEM.

June 29, 1971 F. B. HARLEY 3,588,970

RELEASABLE CLAMPS Filed Feb. 10, 1969 4 Sheets-Sheet 1 INVENTOR Pam B. HARLEM BY ,LJM WMv-AMLg ATTORNEYS June 29, 1971 F. B. HARLEY 3,588,970

RELEASABLE CLAMPS Filed Feb. 10, 1969 4 Sheets-Sheet 2 INVENTOR Fkmuk 8. HARLEY BY Av(mL M+/3M AT ITO R NE Y3 June 29, 1971 HARLEY 3,588,979

RELEASABLE CLAMPS Filed Feb. 10, 1969 4 Sheets-Sheet 3 INVENTOR Fa 1mm 8- Han Luv BY MMww /imm AHORNLYJ June 29 1971 HARLEY 3,588,970

RELEASABLE CLAMPS Filed Feb. 10. 1969 4 Sheets-Sheet 4.

INVENTOR Faun B HAQLEY ATTORNEYS United States Patent Office 3,588,970 Patented June 29, 1971 3,588,970 RELEASABLE CLAMPS Frank B. Harley, Egham, England, assignor to Girdergrip Limited Filed Feb. 10, 1969, Ser. No. 797,815 Claims priority, application Great Britain, Feb. 15, 1968,

Int. Cl. A441) 13/ US. CI. 24-24]; Claims ABSTRACT OF THE DISCLOSURE Releasable clamps are described for use in connecting guys or stays to scaffold constructions. The clamps include pairs of plates in pivotal relationship at least one of the plates having a hook in which the scaffold tube can be inserted and thereafter secured by relative pivotal movement of the plates so as to cause the open end of the hook to be bridged. The plates are arranged with the hooks in opposite hand relationship to receive a scaffold tube simultaneously between them.

This invention relates to releasable clamps and particularly to clamps of the kind which can be employed for the attachment of stays and guys to framework constructions. It is a common problem with large structures particularly those of a free-standing type, i.e. which cannot be tied to a building that these constructions are susceptible to sway due to strong winds. For example it is quite common to use large free standing scaffold constructions when it is necessary to traverse a main road or motorway e.g. during the construction of pylon lines, bridges, fly-overs etc. With such constructions it is necessary to use guy wires and net wires secured at appropriate points to the scaffold constructions and to lead these to tensioning points on the ground. Accordingly it is necessary to provide means for readily and firmly securing these cables to scaffold tubes forming parts of the scaffold construction and the invention is particularly concerned with a clamp which can be readily assembled on to a scaffold tube and have a steel cable or cables connected to it. In this field it is essential to provide clamps of a relatively simple construction which can be readily applied by semiskilled labour in a fool-proof manner and at the same time it is essential that the clamp should be utterly reliable and yet inexpensive.

Further examples of the application of the device are camera towers, lighting masts and all structural steel work during erection.

According to one aspect of the present invention a releasable clamp comprises two pivotally connected parts, for example to which two loads may be respectively applied, each part having a slot extending from its periphery, the parts being pivotable between open and closed positions, first portions of the slots adjacent the respective peripheries of the parts being in alignment in the open position whereby another member may be inserted into the said first portions of the slots in the open position whereafter relative pivotal movement of the parts to the closed position causes at least a section of each of the said first portions of the slots to be covered by another region of the respective other part, second portions of said slots in the closed position being aligned with each other to at least partially surround the other member and prevent its escape via said first portions.

The slots are preferably of substantially L shape in each part and conveniently, for example for the application of the clamp to the scaffold tube, the second portions of the slots each aiford a part circular surface whereby, in the closed position, the two parts define a substantially circular opening.

According to another aspect of the present invention a releasable clamp for attachment to a scaffold tube comprises two pivotally connected fiat parts having a flat surface on each lying adjacent one another whereby the parts are at least partially superimposed upon one another and capable of being pivoted between open and closed positions, each part having a substantially hook-shaped slot extending from its periphery, relatively straight portions of the hook shaped slots adjacent the respective peripheries of the parts being in alignment in the open position whereby the scaffold tube may be inserted into the said straight portions of the slots in the open position whereafter relative pivotal movement of the parts to the closed position causes at least a section of each of the said straight portions of the slots to be covered by another region of the respective other part, curved closed end portions of said slots in the closed position being aligned with each other to afford a substantially circular opening to at least partially surround the scaffold tube and to prevent its escape via said Straight portions.

Each part preferably includes clamping means for the securing of a cable to the part and these clamping means may each comprise a slot extending partially or completely through the part and a transverse bar adapted to be clamped towards the slot to kink a section of cable into the slot.

The invention may be carried into practice in a number of ways but four specific embodiments will now be described by way of example with reference to the accompanying drawings in which;

FIG. 1 shows a releasable clamp according to the present invention which is specifically designed for connection to scaffold tubes and for the application of a pair of high tensile steel cables, the clamp being in an open position and shown ready to receive a scaffold tube;

FIG. 2 shows the clamp of FIGS. 1 and 2 in a position it will occupy on a tube when in a free hanging position;

FIG. 4 shows a different form of releasable clamp in a closed position;

FIG. 5 shows parts of the clamp of FIG. 4 in an open position;

FIG. 6 illustrates a method of latching the parts of a clamp in the closed position;

FIGS. 7 and 8 illustrate a further embodiment respectively in the closed and open positions, and

FIGS. 9 and 10 show another embodiment respectively in the closed and open positions.

The clamp shown in FIGS. 1 and 2 incorporates two pivoted members 10 and 1.1, each formed from A thick steel plate, which are pivoted together at a pivot point '12 by means of a suitable nut and bolt together with appropriate washers. It will be observed, for example with reference to the member 11, that each of the members is of generally hook form having a lower parallel sided portion 15 to which a high tensile steel cable may be connected in a manner to be described and an upper portion 16 having a curved outer periphery 17 and an aperture generally indicated at 18 which has three definable sections, namely a substantially parallel sided section 19 defined between an edge 20 and an edge 21 formed on the end of the upper portion 16. The section 19 merges into an intermediate section 23 which in turn merges into a semi-circular section 24. With the parts as shown in FIG. 1 which may be termed an open position, the parallel sided sections 19 of the two members 10 and 11 are in partial alignment whereas the semi-circular sections 24 are each covered by portions of the other member since these members are bolted together with their hooks in opposite-hand relationship. The intermediate sections 23 of the 3 apertures of the two members are only partially in alignment so that, with the members in the open position, another part such as a scaffold tube, 22 having an external diameter substantially equal to the gap between the edges 20 and 21, can be inserted into the mouths of the tWo sections 19.

Thereafter the tube 22 can be moved towards the pivot point 12 if the two members and 11 are rotated slightly anti-clockwise and clockwise respectively to the intermediate position of FIG. 3. The members can then be pivoted, the member 10 anti-clockwise and the member 11 clockwise, to their respective positions of FIG. 2 which represents a closed position of the clamp. In this position the two semi-circular sections 24 form a generally circular aperture in which the scaifold tube 22 can be received and located and from which it is unable to escape (other than longitudinally) until the parts are restored to their open position of FIG. 1. It is to be noted that in FIG. 2 the tube 22 is further from the pivot 12 than in FIG. 3. Hence in FIG. 3, if no load is applied to the members 10 and 11 it is found that they will maintain the position shown in this figure since although the centres of gravity of the members are such that they are tending to open the clamp, these forces are being resisted by the load which is required to lift the clamp, with respect to the tube 22, to the FIG. 1 position. This is found to be a very satisfactory way of temporarily retaining the clamp on the tube until a load is applied to one or other member 10 or 11.

Each lower parallel sided portion 15 of the two members 10 and 11 has in it a slot which co-operates with a bar 31, which as shown on the left in FIG, 2, can be pivoted aside from the position of FIG. 1 by virtue of an open ended slot 32 in one edge thereof, the slot 32 and a spaced hole in the bar 31 being arrranged to receive a pair of bolts 34 and 35 as shown in FIG. 1 in order that the bar 31 can be clamped towards its respective member 10 or 11. In order to secure a steel cable to one of the members the bar 31 is pivoted to the position shown in FIG. 2 and a section of the cable laid in line with the slot 30, the cable being slightly kinked if possible to cause the cable partially to lie in the slot 30. Thereafter by suitable slackening of the nut of the bolt 34, or if necessary by complete removal thereof, the bar 31 can be swung to overlie that section of cable aligned with the slot 30 whereafter tightening of the bolts 34 and 35 will draw the cable firmly towards the face of the member 10 or 11 and in so doing cause the section of cable in line with the slot 30 to be well kinked into the slot to form a very secure connection capable of withstanding considerable axial loads on the cable.

Clamps of the form shown in FIGS. 1 and 2 when used in the orientation shown can be applied, for example, to horizontal scaffold tubes which may be incorporated for instance in large scaffold constructions which require the use of stays in order firmly to secure the constructions to the ground. By the use of the particular coupling shown a pair of cables can be applied to the members 10 and 11 and used as stays or guys subtending an angle between them of 145 so that the tension in the cables applies loads to the members 10 and 11 in directions which intersect adjacent the pivot bolt 12.

The form of coupling shown is extremely simple and is capable of very quick attachment or detachment from scaffold tubes in particular and once attached and a tension applied to each of the two members of the coupling in the requisite direction or directions no inadvertent release of the coupling is possible. It is envisaged that for large scaffold constructions, for example as are often used in open country e.g, for traversing main roads or motor-ways during erection of pylon lines, bridges etc., a number of couplings of this form would be used in order to provide the whole construction with 4 adequate staying to be able to resist gale force winds in complete safety.

Whilst it has been stated above that a load is applied in many circumstances to both members of the clamp, if desired a single load may be applied merely to one member.

FIGS. 4 and 5 show a different form of clamp for example for use in hoisting tubes. The clamp comprises a pair of spaced plates forming one part of the clamp and a single hook-plate 41 situated between the plates 40 and forming a second member of the clamp. At their upper ends the plates are separated by a stud 43 to which a loop of cable may be secured. The plates 40 are spaced apart, and extending between them is a pin 42 having a cross-section which is generally rectangular with semicircular ends as shown in FIG. 5. This pin cooperates with a keyhole shaped slot 44 formed in a head portion 45 of the hook-plate 41. The keyhole slot 44 has an enlarged rounded end 47 merging with a slotlike portion 48. The diameter of the rounded end 47 is slightly greater than the length of the pin 42 so that, when the members are in the position of FIG. 5, they can be pivoted with respect to one another about the pin 42. When the hook-plate 41 is pivoted anti-clockwise in FIG. 5 to the position in which the slot 48 is vertical the hook-plate 41 can drop so that the slot 48 embraces the pin 42 thereafter preventing relative rotation of the two members of the clamp. To return the plates from FIG. 4 position to the FIG. 5 position it is necessary first to lift the hook-plate 41 until the pin 42 is received in the rounded end 47 of the keyhole slot 44 whereafter the hook-plate 41 can be turned clockwise to a released position. In the released position, the hook-plate 41 can have a tube, rod or bar, passed into a hook 50 formed at its free end and thereafter the parts restored to the FIG. 4 position in which the lower ends of the plates 40, which are of reduced form as indicated in FIG. 5, close the mouth of the hook 50 to retain the tube, rod or bar within the hook '50.

FIG. 6 illustrates a form of latching which may be incorporated to hold the parts in the closed position of FIG, 4. In this case the plates 40 have an intermediate member 51 extending between them at their upper ends and secured to them by a transverse rivet 52. The upper end of the intermediate member 51 has a hole 53 by which the clamp can be secured to another part e.g. a cable loop as in the case of the embodiment of FIGS. 4 and 5. The lower end of the intermediate member 51 carries a spring loaded plunger 54 which co-operates with a recess 55 formed on the upper end of the plate 41.

FIGS. 7 and 8 illustrate a further embodiment which is similar in function to the embodiments of FIGS. 4 and 5 but in this case the outer members 40A are formed with hook-like lower end portions 55 spaced apart by a spacing block 56 secured to the plates 40A by rivets 57. In this case therefore the hooked end 50 of the second member 41 is received between the portions 55 of the plates 40A and is securely trapped therebetween as shown in FIG. 7.

Finally FIGS. 9 and 10 show a type of clamp having three main parts. Thus it includes a member 60 formed by a pair of spaced plates, together with a pair of identical hooks 61 and 62 arranged with their hook openings 62 in opposite hand relationship so that in the closed position of FIG. 9 they define an opening 63 within which a tube 64 may be trapped. By upward and then outward movement of the books 61 and 62 the parts can be moved to the open position of FIG. 10 to enable the release of the clamp from the tube or for the securing of the clamp to a tube as the case may be.

What we claim as our invention and desire to secure by Letters Patent is:

1. In a releasable clamp for attachment to an elongated member having a predetermined diameter, said clamp comprising two hook-shaped parts pivotally connected for relative swinging motion about a common axis, each part having a flat surface facing the fiat surface on the other member and lying in a plane transverse to said axis, and each part defining a slot having a relatively narrow outer portion and a wider inner portion, said parts being relatively pivotable between a first position in which said slots are aligned to the extent that said elongated member can be passed through said narrow portions into said larger portions, and a second position in which the narrow portion of the slot in each part is aligned with a solid portion of the other part, whereby removal of said elongated member through said narrow recess portions is prevented, the improvement according to which said parts are so shaped and dimensioned that when said elongated member occupies a position within the wider portions of said slots completely clear of said narrower portions said hookshaped parts are blocked from moving to a position in which said narrower slot portions are aligned to an extent suflicient to pass said elongated member, so that in order to remove an elongated member from said slots said narrow portions must first be partially aligned, and said elongated member caused to move partially into said narrow portions, after which said narrow portions may be brought more fully into alignment, and said elongated member passed therethrough.

2. A releasable clamp as claimed in claim 1 in which the slots are substantially L shape in each part.

3. A releasable clamp as claimed in claim 2 in which the inner portions of the slots each alford a part circular surface whereby, in the closed position, the two parts define a substantially circular opening.

4. A releasable clamp as claimed in claim 1 in which each part includes clamping means for the securing of a cable to the part.

5. A releasable clamp as claimed in claim 4 in which the clamping means each comprise a slot extending partially or completely through the part and a transverse bar adapted to be clamped towards the slot to kink a section of cable into the slot.

References Cited UNITED STATES PATENTS 249,177 11/1881 Healey 24248X 1,353,134 9/1920 Shilfer et al. 24241CH 1,369,647 2/1921 Gendron 24241CH 1,626,642 5/1927 Stockstad 24242 1,680,551 8/1928 King 2473.13UX 2,796,651 6/1957 Ratcliff 24241PS FOREIGN PATENTS 4,712 1915 Great Britain 24241 74,422 5/1932 Sweden 24230.5

DONALD A. GRIFFIN, Primary Examiner 

